The medical records of 21 dogs with concurrent immune-mediated haemolytic anaemia (imha) and severe thrombocytopenia (defined as an automated platelet count of less than 50 × 109/l, confirmed by the examination of a blood smear) were reviewed. Their mean (sd) age was 5·8 (2·5) years. When compared with the 24,759 dogs in the hospital population for the same period Airedale terriers and dobermanns appeared to be over-represented with odds ratios of 22·5 (95 per cent confidence interval [ci] 5·2 to 97·9) and 7·6 (95 per cent ci 1·8 to 32·7) respectively. The median duration of the dogs' clinical signs was seven days, with a range from one to 17 days. Eleven of the dogs had a history of a tendency to bleed, and 15 had evidence of bleeding when examined. Twenty of the 21 dogs had been treated with glucocorticoids, nine with vincristine, and seven with azathioprine. Their median stay in hospital was four days, with a range from one to 17 days. The median period for which they survived after admission to hospital was five days, with a range from one to 558 days, and 16 of the 21 dogs had died or been euthanased within 30 days of their admission.